A Technical Review on Performance and Emissions of Compressed Natural Gas - Diesel Dual Fuel Engine

In view of the depletion of energy and environmental pollution, dual fuel technology has caught the attention of researchers as a viable technology keeping in mind the increased availability of fuels like Compressed Natural Gas (CNG). It is an ecologically friendly technology due to lower particulate matter (PM) and smoke emissions and retains the efficiency of diesel combustion. Generally, dual fuel technology has been prevalent for large engines like marine, locomotive and stationary engines. However, its use for automotive engines has been limited in the past due to constraints of the limited supply of alternative fuels. CNG is a practical fuel under dual-fuel mode operation, with varying degree of success. The induction method prevents a premixed natural gas-air mixture, minimizes the volumetric efficiency and results in a loss of power at higher speeds. Under lower engine operating temperatures, at low-intermediate loads, the oxides of nitrogen (NO_x) emissions reduce however hydrocarbon (HC) and carbon monoxide (CO) emissions are significantly increased. This paper reviews the fuel properties of CNG comparison with diesel, methods available to use CNG in automobiles, combustion, performance and emissions of CNG- diesel dual fuel engine.